Expansion device



March 19, 1929. w DANN 1,705,722

EXPANSION DEVICE Filed Nov 10, 1922 Fig. 5.

WITNESSES: I INVENTOR Walter M Damn wwy WALTER M. DANN, OF WILKINSEBURG, PENNSYLVANLL ASSIGNOE E0 WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, .A CORPORATION OF-IPEN'NSYL- VANIA.

Application filed November 10, 1922. Serial No. 600,068.

My invention relates to expansion devices to be employed in connection with electrical apparatus, such, for example, as transformers, circuit breakers and the like.

The embodiment of my present invention is similar in certain respects to the expansion device shown and described in my copending application, Serial No. 555,510, filed April 18, 1922.

My invention has for one of its objects to provide a simple and ellicient arrangement whereby inert gas is maintained in contact with the insulating fluid surrounding electrical apparatus.

A second object of my invention is to provide an expansion device for electrical apparatus which effectually prevents the admission of air and moisture to the interiors of I containers for such apparatus.

A third object of my invention is to provide an expansion device that may be readily adapted to existing apparatus without material alterations.

In the operation of oil-insulated or oilcooled apparatus, it is highly desirable to prevent the formation of explosive mixtures of air and hydrocarbon gases within the containers. It has been proposed, heretofore, to completely fill the containers with oil.

The presence of oil under pressure in the upper part of the main container such as is the case with certain forms of expansion devices, where the container is entirely filled with oil, results in leakage and seepage at joints and through bushings and fittings which generally form part of the cover. This leakage is objectionable on account of the unsightly appearance of the apparatus as well as the loss of oil.

My invention comprises the employment of an expansion device which constitutes a liquid seal for. an inert gas that is maintained in the space above. the'insulating fluids of transformers or other electrical apparatus. The

' portion of the expansion device that is in communication with the main tank of the transformer contains a deoxidizing agent agent which produces and maintains, by diffusion, an inert gas within the closed system. The formation of an explosive mixture of air and hydrocarbon gases is thereby efi'ect'ually prevented.

In the accompanying drawings,

Figure 1 is a view, partially in elevation V and partially in section, of a transformer tank and an expansion device constructed in accordance with my invention operatively connected thereto;

Fig. 2 is a view in transverse section of the expansion device, taken along the line IIII of Fig. 1; and Y Fig. 3 is a diagrammatic view of a plurality of transformers with a single expansion device connected thereto. Y

A tank 1 for a transformer, circuit breaker, or other electrical apparatus, may be partially filled with insulating fluid, such, for example,as oil, indicated at 2, leaving a space 3 above the oil. The electrical apparatus which may be enclosed by the tank 1 is omitted for the sake of clearness, the details of such apparatus constituting no part of the present invention.

An expansion device 4, which is connected to. the space 3 of the tank 1 by means of a pipe lme 5, comprises two superposed compartments or chambers 6 and 7 that are normally partially filled with liquid, such, for example, as oil, indicated respectively at '8 and 9. The lower chamber 7 is connected. at its upper portion, to the pipe line 5. The chamber 7 is connected, at its lower portion, to a corresponding portion of the upper chamber 6 by means of a pipe 10, whereby transfers of oil bet-ween the two chambers may be effected.

The lower chamber 7 is provided with a removable container 12 for a suitable deoxidizing and dehydrating agent, such, for example, as phosphorus The container 12 is connected to a removable cover member 13, which closes a suitable opening 1 1 through which the container'lZ may be withdrawn for inspection or replacement of the deoxidizing agent. The space above the insulating oil in the lower chamber communicates with an indicator 15, through which the condition of the inert gas may be observed or indicated by any suitable means, such, for example, as

main tank cause transfers of oil from the one chamber to the other. The pipe line 5 is provided with a valve 17, whereby communication between the main tank 1 and the chamber 7 may be cut off to prevent the escape of the inert gas from the tank when it is desired to open the chamber 7 for the purpose of inspecting or replenishing the su ply of deoxidizing agent. I

t may be assumed that the tank 1 and the chambers 6 and 7 have been connected and that the several spaces above the oil contained in the various compartments are occupied by ordinary air. It may be assumed further that the container 12 has been provided with a suitable supply of deoxidizing and dehydrating agent. The latter operates in accordance with its well-known properties to absorb oxygen and moisture from the air, leaving the gas contained in the chamber 7 the space 3 and the pipe line 5 substantially nitrogen, which is an inert gas.

During the operation of the electrical apparatus, variations in temperature occur, causing the oil 2 to change its volume and, in case of increased volume, to forcea portion of the gas contained in the space 3 into the chamber 7. This action causes oil to be transferred from the chamber 7 through the pipe 10 into the chamber 6. The increase in volume of the oil-in the chamber 6 causes air to flow through the vent 16 into the atmosphere. The capacity of the expansion device 4 is such as to permit fluctuations in volume of the oil 2 as may occur during the normal operation of the a paratus.

When the temperature 0? the oil 2 decreases and the pressure is lowered, gas from the tank 7 flows through the pipe line 5 to the space 3. Oil is transferred from the chamber 6 to the chamber 7 and air enters through the vent. 16 into the chamber 6. The transfer of oil from the one chamber to the other compensates for variations in pressure produced by variations in temperature in the tank 1.

The air which enters the chamber 6 by reason of decrease in temperature in the main tank 1 may contain a certain proportion of moisture which may be-partia-lly taken up by the oil 8. This moisture may be transferred to a greater or less degree to the oil in the chamber 7. Ineither chamber, the greater portion of the moisture will, by reason of its weight, settle to the bottom, where it may be drawn off by a suitable valve. Such small amount of moisture as may be carried in suspension in the oil and might evaporate in the chamber 7 is, however, absorbed by the dehydrating agent to maintain the gas there in in a dry and inert state.

While I have thus far described an expansion' device constructed in accordance with my invention as a plied toa-single transbe connectedto a number of transformers or other electrical apparatus. In case it is desired to apply an expansion device to a battery of transformers, such, for example, as the transformers 17, diagrammatically shownin Fig- 3, it is only necessary that the chamber 7 of an expansion device 4 be connected by suitable pipe lines 19 to the spaces above the oil in the several transformer tanks. A

single supply of deoxidizing and dehydrating agent will produce and maintain a supply of inert gas for all of the transformers.

An expansion device constructed in accordance with my invention operates to prevent deterioration of the insulating fluid by reason of oxidation by reason of contact with air or the presence of moisture. It will also operate to improve the insulating properties of the fluid by extracting from it the oxygen contained in suspension. Injury to the electrical apparatus by the ignition of an explosive mixture upon the occurrence of a fault is prevented by the production and maintenance of an inert gas in contact with the insulating oil.

The provision of a gas-filled space above the insulating liquid which communicates with the expansion device operates to cushion any forces set up by the sudden evolution of gases resulting from an internalfault below the level of the liquid. The expansion device constitutes a liquid seal without moving parts.

The deoxidizing and dehydrating material may be easily and conveniently inspected or replaced without interruption of service by the provision of means for isolating the expansion device from the main tank at desired times. The location of the deoxidizing agent in the auxiliary apparatus instead of in the main tank constitutes an important improvement.

I claim as my invention 1. An expansion device comprising two chambers partially filled with liquid to constitute a seal, communicating means whereby liquid may be transferred from one chamber to the other, one of said chambers having an opening through which fluid pressure may be communicated from an external source and gases of different characteristics occupying the respective chambers.

2 An expansion device comprising two chambers partially filled with liquid to con stitute a seal, communicating means whereby liquid may be transferred from one chamber to the other, one of said chambers having an opening through which fluid pressure may be communicated from an external source, inert gas in said one chamber above the liquid therein, the other of said chambers having communication with the atmosphere whereby variations in pressure applied to said one chamber may be compensated for without the admission of air thereto.

3. The combination with a tank for containing electrical apparatus and an insulating fluid, of two communicating chambers for containing a liquid to constitute a seal..one of said chambers communicating with said tank above the level of the insulating fluid and said one chamber containing an agent for producing an inert gas.

4. The combination with a main tank for containing electrical apparatus and insulating oil, of an auxiliary tank for containing oil, communicating means for connecting said tanks above .the respective levels of oil therein, a container for a deoxidizing agent in said auxiliary tank for producing an inert gas therein. a chamber containing oil and communicating at its lower portion with the lower portion of said auxiliary tank and, at its upper portion, with the atmosphere, whereby variations in volume of the oil in said main tank cause exchanges of oil between said auxiliary tank and said compartment without the admission of air to said main tank.

5. An expansion device comprising two superposed communicating chambers, one of said chambers being arranged for communication with an external device and having a deoxidizing agent therein, the other of said chambers having an opening into the atmosphere, and both of said chambers being par tially filled with liquid to constitute a seal.

/ 6. An expansion device comprising two chambers partially filled with liquid to constitute a seal, communicating means whereby liquid may be transferred from one chamber to the other, one of said chambers comprising a plurality of openings through one of which fluid pressure may be communicated from an external source, a movable cover for another of said openings, a tray connected to said cover, and a deoxidizing agent in said tray.

7. The combination with a casing containing a submerged electrical device, of a plurality of chambers partially filled with liquid to constitute a seal, communicating means whereby liquid may be transferred rom one chamber to another, a removable tray in one' of said chambers, a deoxidizing agent in said tray, a conduit communicating with said one of said chambers and with said casing, and a valve interposed in said conduit.

In testimony whereof, I have hereunto.

subscribed my name this 4th day of November 1922.

WALTER M. DANN. 

